Expansion-assisting delivery system for self-expanding stent

ABSTRACT

A delivery system for a self-expanding stent includes a catheter having a distal end and being configured to retain a self-expanding stent proximate the distal end. The delivery system also includes an inflatable device provided on the catheter and positioned proximate the distal end. The inflatable device, typically a balloon, is configured to selectively assist the self-expanding stent with radially expansion. The catheter includes a tubular member and an outer member coaxially positioned about the tubular member. The outer member can slide relative to the tubular member in an axial direction. The outer member is configured to retain a self-expanding stent in a radially-compressed position and to release the self-expanding stent to a radially-expanded position. The delivery system may also include a holding sleeve provided on the tubular member, spaced from the distal end of the catheter, and configured to hold the self-expanding stent. The delivery system preferably includes a loading funnel configured to be removably attachable to the distal end of the tubular member and configured to assist with radial compression of the self-expanding stent and advancement of the self-expanding stent within the outer member.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a system for delivery of a stent intothe body of a patient. More particularly, the present invention relatesto an expansion-assisting delivery system for a self-expanding stent.

2. Description of Related Art

Stents are well-known endoprotheses. A conventional endoprotheses stentincludes a radially-expandable, tubular structure. The tubular structurecan expand radially from a compact form for delivery to an expanded formfor implantation. Radial expansion of the stent effects implantationinto the tissues of a vessel wall being repaired or bridged. The vesselcan include, for example, a body canal, blood vessel, duct, otherpassage, and the like.

A conventional endoprosthetic stent can be mechanically expansive orself-expansive. A conventional mechanically-expansive stent initiallypossesses a radially compact form. The stent is loaded onto a deliverysystem, such as a catheter. Typically, an expandable balloon ispositioned in the tubular structure of the stent. After delivering thestent to the region of a vessel being repaired or bridged, the balloonis expanded, thereby implanting the stent onto the vessel wall. Toexpand the stent, the balloon must be connected to a fluid source bymeans of a lumen or some other tubular structure.

A conventional self-expansive stent initially possesses aradially-expanded form. The stent is compressed radially as it isassembled onto a delivery system. Typically, an outer tubular structureretains the compressed stent until it is delivered to the region of avessel being repaired or bridged. The stent is then released from itscompressed state and self-expands to implant onto the vessel wall. Anexpandable balloon is not required to expand the stent. However, incases where a stricture of the vessel is difficult to repair or bridge,a physician may use a balloon to assist with expansion of the deployedstent.

Generally, when a balloon is used to assist with expansion of aself-expanding stent, the conventional stent delivery system is removedafter the stent is successfully deployed. Then, either a separatesingle-use balloon catheter or a second delivery system having anexpandable balloon is delivered to the sight of the stent. In eitherevent, a physician would be slowed by this process of removing the stentdelivery system and delivering the balloon.

Conventional stent delivery systems generally include a minimaltransverse dimension so that a distal end of the delivery system can benavigated through and along a patient's lumens, or vessels, either in apercantaneous insertion procedure or through the working channel of anendoscope or laparoscope. Often times, physicians use a delivery systemin combination with a medical guidewire. Typically, in transluminalprocedures, the physician directs a guidewire through narrow passages,or vessels, in a patient's body using a steering mechanism provided at aproximal end outside of the body. The physician monitors the travel andposition of a distal end of the guidewire by a fluoroscope or otherknown device. Once the distal end of the guidewire reaches a desiredposition, the steering mechanism is removed and the delivery system isdirected into the vessel along the guidewire. Other procedures fordirecting catheters or similar devices into larger vessels of the body,such as the esophagus, are also well known.

Thus, use of a conventional delivery system for a self-expanding stentin combination with a guidewire and a post-deployment expandable balloonwould require the following time-consuming procedures: delivery of theguidewire; delivery and deployment of the stent; removal of the stentdelivery system; delivery and activation of an expandable balloondevice; and removal of the balloon delivery system and guidewire. Therepeated insertion and removal of delivery systems prolongs theprocedure and thereby increases the trauma and risk to the patient andincreases costs.

SUMMARY OF THE INVENTION

To overcome the disadvantages of the prior art, and in accordance withthe purposes of the invention, as embodied and broadly described herein,there is provided an expansion-assisting delivery system for aself-expanding stent. The delivery system includes a catheter having adistal end and being configured to retain a self-expanding stentproximate the distal end. The delivery system also includes aninflatable device provided on the catheter and positioned proximate thedistal end. The inflatable device is configured to selectively assistthe self-expanding stent with radial expansion. In a preferredembodiment of the delivery system, the inflatable device is a balloon.

In accordance with the present invention, the catheter includes atubular member and an outer member coaxially positioned about thetubular member. The outer member can slide relative to the tubularmember in an axial direction. The outer member is configured to retain aself-expanding stent in a radially-compressed position and to releasethe self-expanding stent to a radially-expanded position. The deliverysystem may also include a holding sleeve provided on the tubular memberand spaced from the distal end of the catheter. The holding sleeve canbe configured to hold the self-expanding stent.

In a preferred embodiment, the delivery system also includes a loadingfunnel configured to be removably attachable to the distal end of thetubular member. The loading funnel may be configured to assist withradial compression of the self-expanding stent and advancement of theself-expanding stent within the outer member.

Another preferred embodiment of the delivery system includes a spacingjacket coaxially positioned about the tubular member and inside theouter member. In yet another preferred embodiment, the delivery systemincludes a fluid port configured to receive a fluid and direct the fluidto a region between the tubular inner member and outer member.

In another preferred embodiment, the tubular inner member of thedelivery system includes a first marker band indicating a positioncorresponding to a proximal end of a self-expanding stent, a secondmarker band indicating a position corresponding to a re-constrain limitof a partially-expanded, self-expanding stent, and a third marker bandindicating a position corresponding to a distal end of a self-expandingstent. The third marker band is positioned between the first marker bandand the third marker band. The tubular inner member may define first andsecond lumens, one receiving a guidewire, and the other providing afluid passage to the inflatable device.

Another aspect of the invention provides a self-expanding stent incombination with a preferred embodiment of the delivery system of theinvention.

In yet another aspect, the invention provides a method for implantationof a self-expanding stent including providing a preferred embodiment ofthe delivery system of the invention, delivering the delivery system toa region of a vessel to be repaired, implanting the self-expanding stentinto a wall of the vessel to be repaired, and inflating the inflatabledevice to assist expansion of the self-expanding stent.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute partof the specification, illustrate a presently preferred embodiment of theinvention and, together with the general description given above anddetailed description of the preferred embodiments given below, serve toexplain the principles of the invention.

FIG. 1 is a plan view of a preferred embodiment of a partially-assembleddelivery system according to the invention;

FIG. 2 is a plan view of a preferred embodiment of an assembled deliverysystem according to the invention;

FIG. 3 is a partial, sectional view of the delivery system illustratedin FIG. 2; and

FIG. 4 is an alternative partial, sectional view of the delivery systemillustrated in FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference now will be made in detail to the present preferredembodiments of the invention, examples of which are illustrated in theaccompanying drawings, in which like numerals designate like elements.

In accordance with the present invention, there is provided a deliverysystem for a self-expanding stent. As embodied herein and shown in FIGS.1-3, the present invention includes a catheter 10 adapted to deploy aself-expanding stent. The stent may, for example, repair or bridge adamaged vessel of a patient's body. The catheter 10 includes an innermember 20 and an outer member 40. Preferably, the inner and outermembers 20, 40 are tubular-shaped. In a preferred embodiment, a portionof inner member 20 may be formed of stainless steel. However, theinvention in its broadest sense is not limited by the shape, size,composition, or type of the inner member 20.

FIG. 1 illustrates the delivery system with the outer member 40 removed.In FIG. 1, the inner member 20 has a proximal end 22 and a distal end24. Spaced from the distal end 24, the inner member 20 includes aholding sleeve 26. The holding sleeve 26 is preferably coaxially mountedabout the inner member 20 and is sized and configured such that aself-expanding stent 90 can be placed around it. The holding sleeve 26can retain the positioning of the stent 90 during delivery andre-constrain procedures by cooperating with the outer member 40 toprevent axial movement of the stent.

The inner member 20 is also provided with an inflatable device 28positioned between the holding sleeve 26 and the distal end 24.Preferably, the inflatable device 28 is coaxially mounted about theinner member 20 and, when deflated, has a small enough radial componentthat a coaxially-mounted, self-expanding stent can pass over theinflatable device 28. The inflatable device 28 is preferably a balloon,such as a biliary balloon or the like known in the art. The inflatabledevice 28 may also function as a holding sleeve 26 in someconfigurations, negating the need for a separate holding sleeve device26.

As shown in FIG. 1, the inner member 20 preferably includes a firstlumen tube 32 and a second lumen tube 34. The first lumen tube 32 isconfigured to receive a medical guidewire (not shown), and the secondlumen tube 34 provides a fluid passage to the inflatable device 28. Theconfiguration of the lumen tubes can be reversed such that the firstlumen tube provides a fluid passage to the inflatable device 28 and thesecond lumen tube receives a medical guidewire.

In a preferred embodiment of the invention, the distal end 24 of theinner member 20 includes a tapered tip 36. The tapered tip 36 mayprovide easier delivery and maneuverability, particularly when using thedelivery system in combination with a medical guidewire. In addition,the tapered tip 36 includes a surface 38 extending radially outward fromthe inner member 20 and forming a seat against which the outer member 40can rest.

FIG. 2 illustrates the delivery system with the outer member 40coaxially positioned about the inner member 20. The outer member isslidably mounted about the inner member to permit relative axialmovement between them. As shown in FIG. 2, the catheter 10 may alsoinclude a loading funnel 42 removably attached to a distal end 44 of theouter member. The loading funnel 42 is sized and shaped to assist withradial compression of a self-expanding stent as the stent is loaded ontothe delivery system.

FIG. 3 illustrates the delivery system in combination with aself-expanding stent 90. The stent 90 may be made of bioabsorbablepoly-l-lactide filaments braided in a tubular mesh configuration.However, the invention in its broadest sense is not limited by theshape, size, composition, or type of the self-expanding stent 90.

A self-expanding stent 90 may be operatively loaded onto the deliverysystem at the distal end of the catheter 10, passing over the inflatabledevice 28 and holding sleeve 26. As shown in FIG. 3, the self-expandingstent 90 is retained in a radially-compressed position by the outermember 40, and the inflatable device 28 is provided on the catheter 10between the self-expanding stent 90 and the distal end of the catheter10. As shown in FIG. 4, the inflatable device 28 may alternatively bepositioned beneath the distal portion of the self-expanding stent 90.The outer member 40 releases the self-expanding stent 90 to aradially-expanded position as the outer member 40 slides relative to theinner member 20 in a direction away from the seat 38.

In a preferred embodiment, the delivery system includes a spacing jacket52 coaxially positioned about the inner member 20 and inside the outermember 40. The spacing jacket 52 may reduce snaking, coiling, ortwisting of the inner member within the outer member, particularlyduring the delivery through a tortuous anatomy.

According to another preferred embodiment of the delivery system, theinner member 20 includes first, second, and third marker bands 62, 64,66. As shown in FIG. 1, the third marker band 66 is positioned nearestthe distal end 24 of the inner member 20 and the second marker band 64is positioned between the first maker band 62 and the third marker band66.

In a preferred embodiment, a self-expanding stent extends from the firstmarker band 62 to the third marker band 66, in which case, the firstmarker band 62 indicates the position of a proximal end of theself-expanding stent 90, and the third marker band 66 indicates theposition of a distal end of the self-expanding stent 90. The secondmarker band 64 indicates a re-constrain limit of a partially-expanded,self-expanded stent.

The re-constrain limit signifies the final point to which a stent can bepartially-expanded while still providing a physician or other operatorwith the ability to successfully re-constrain, re-position, andre-expand the stent. That is, once a self-expanding stent is loaded ontothe delivery system, a physician can move the outer member 40 in anaxial direction away from the distal end 24 of inner member 20 to allowexpansion of the self-expanding stent. As long as the outer member 40does not reach the second marker band 64, the physician may re-constrainthe self-expanding stent by moving the outer member 40 in an axialdirection toward the distal end 24 of inner member 20. However, once thedistal end of the outer member 40 passes the second marker band 64. Thepossibility of stent deployment or slip with respect to the deliverysystem increases.

In an alternative embodiment, as shown in FIG. 3, the stent 90 may notextend to the seat 38 of the tapered end 36 of the inner member 20. Inthis case, a stent marker band 68 indicating the position of a distalend of the stent 90 may be provided on the stent 90 itself.

The marker bands 62, 64, 66, 68 are preferably formed of a material thatwould facilitate imaging during delivery of the delivery system anddeployment of the stent. For example, the marker bands 62, 64, 66, 68may be radiopaque marker bands or the like.

In a further preferred embodiment, the delivery system includes a fluidport 72. The fluid port 72 may be a conduit having a stopcock forconnecting a syringe or any other device known in the art. The fluid canbe used to flush the region between the inner member 20 and outer member40.

According to another aspect, the invention includes a method forexpansion-assisted implantation of a self-expanding stent. The method ofthe invention utilizes a catheter having coaxial inner and outer membersaccording to an embodiment described above. Using sterile techniques, aself-expanding stent is loaded onto the catheter. To load the stent, aloading funnel is removably attached to a distal end of the outermember. The distal end of the outer member is slidably retracted awayfrom the distal end of the inner member in the axial direction of thecatheter. A physician causes relative movement between the inner memberand the outer member with loading funnel by holding the inner member at,for example, the distal end or proximal end and slidably moving theouter member relative to the inner member in an axial direction awayfrom the distal end of the inner member.

As the outer member is retracted, a holding sleeve mounted about theinner member is exposed. A physician or other user passes the stent overthe tip of the distal end of the inner member and onto the holdingsleeve. To do so, the user gently compresses the stent in a radiallydirection and fits it into the loading funnel until a proximal end ofthe stent reaches a proximal, or trailing, marker band. While holdingthe stent stationary in a radially-compressed configuration, the loadingfunnel is advanced back toward the distal end of the inner member.Again, the relative movement between the inner member and the outermember with loading funnel is effectuated by holding the inner memberat, for example, the distal end or proximal end and slidably moving theouter member relative to the inner member in an axial direction towardthe distal end of the inner member. The outer member is advantage untilthe stent is fully constrained between the inner member and outer memberand between the holding sleeve and outer member.

The user delivers the delivery system along a medical guidewire orthrough an endoscope or laparoscope to the area of the vessel to berepaired or bridged. Once delivered to the appropriate location, thestent is released and allowed to self-expand, thereby implanting itselfonto the vessel wall. Release is effectuated by sliding the outer memberin a direction away from the distal end of the inner member. Asdiscussed above, the stent can be successfully re-constrained,re-positioned, and re-expanded if desired, provided that the outermember is not moved beyond the re-constrain limit, or second markerband, in a direction away from the distal end of the inner member.

After the stent has been implanted, a physician or other user maydetermine that the stent is not sufficiently expanded. Thisdetermination may be accomplished with known imaging techniques such as,for example, the use of radiopaque markings on the stent. The deliverysystem of the above embodiments provides the user with the ability toselectively assist an incomplete or improper expansion by using theinflatable device provided on the catheter. Instead of requiring removalof the delivery system and delivery of an expansion balloon, thedelivery system of the invention includes re-positioning of thealready-deployed delivery system so that the inflatable device isproperly aligned with the self-expanded stent. Since the inflatabledevice is positioned adjacent or beyond the distal end of the stent,re-positioning of the delivery system does not entail any furtherinvasion into the patient's anatomy.

Typically, the inflatable device is properly positioned by slightlyretracting the delivery system from the point of implantation of thestent. A fluid source, such as an air or saline source, supplies fluidto expand the inflatable device by way of the first or second lumentube, depending on the system configuration. The inflatable deviceassists with complete and proper expansion of the stent. The inflatabledevice is then deflated prior to the delivery system being withdrawnfrom the patient's anatomy.

In accordance with an embodiment of the invention, the delivery systemmay include an inflatable device extending over the entire length of theself-expanding stent and coated with a tacky material. If the materialwas tacky enough to retain the stent during deploy and re-constrainprocedures, the holding sleeve could be eliminated.

It should also be appreciated that a physician or other user may notneed to use the inflatable device for every stent implantation. However,the delivery system of the invention makes the inflatable deviceavailable for selective usage by the physician. Therefore, the deliverysystem of the invention eliminates the need for an additional balloondelivery device and an additional step in the procedure. As a result,the delivery system reduces the implantation procedure time. Moreover,the delivery system of the invention ensures that the appropriate sizeinflatable device corresponding to the particular self-expanding stentis available for use, reducing the chance of over-dilating a vessel.

While this invention has been described with specific embodimentsthereof, it is evident that many alternatives, modifications, andvariations will be apparent to those skilled in the art. Accordingly,the preferred embodiments of the invention as set forth herein isintended to be illustrative, not limiting. Various changes may be madewithout departing from the spirit and scope of the invention.

1-28. (canceled)
 29. A delivery system for a self-expanding stent, thedelivery system comprising: an inner member having a distal end, theinner member being configured to retain a self-expanding stent proximatethe distal end, the inner member including a marker band disposedbetween a distalmost leading end of the self-expanding stent and atrailing end of the self-expanding stent, wherein the marker bandindicates a re-constrain limit of a partially-expanded, self-expandingstent; an outer member positioned about the inner member, the outermember being slidable relative to the inner member in an axialdirection; a holding sleeve positioned within an interior of the stentso as to retain the positioning of the stent; and a single inflatabledevice positioned about the inner member, wherein the inflatable deviceis disposed solely between the holding sleeve and the distal end of theinner member.
 30. The delivery system of claim 29, wherein the innermember includes a second marker band corresponding to a proximal end ofa self-expanding stent, and a third marker band corresponding to adistal end of the self-expanding stent.
 31. The delivery system of claim29, wherein the inflatable device is a balloon configured to selectivelyassist the self-expanding stent with radial expansion.
 32. The deliverysystem of claim 29, wherein at least a portion of the self-expandingstent overlaps a portion of the inflatable device prior to deployment ofthe self-expanding stent.
 33. The delivery system of claim 29, whereinthe outer member is configured to retain the self-expanding stent in aradially-compressed position and to release the self-expanding stent toa radially-expanded position.
 34. The delivery system of claim 29,further comprising a loading funnel, the loading funnel configured to beremovably attachable to the distal end of the outer member, and toreceive the stent therein as the stent is loaded onto the deliverysystem.
 35. The delivery system of claim 34, wherein the loading funnelis configured to assist with radial compression of the self-expandingstent and advancement of the self-expanding stent within the outermember.
 36. The delivery system of claim 29, further comprising aspacing jacket coaxially positioned about the inner member and insidethe outer member.
 37. The delivery system of claim 29, furthercomprising a fluid port, the fluid port configured to receive a fluidand direct the fluid to a region between the inner member and the outermember.
 38. The delivery system of claim 29, wherein the inner memberdefines a first lumen and a second lumen, one of the first lumen and thesecond lumen configured to receive a guidewire, and the other of thefirst lumen and the second lumen providing a fluid passage to theinflatable device.
 39. The delivery system of claim 30, wherein at leastone of the first, second, and third marker bands is a radiopaque markerband.
 40. In combination, a self-expanding stent and a delivery systemfor the self-expanding stent, the combination comprising: the deliverysystem of claim 29; and a self-expanding stent mounted on the deliverysystem.
 41. A method for implantation of a self-expanding stent, themethod comprising: providing a delivery system comprising: aself-expanding stent; an inner member having a distal end, the innermember being configured to retain a self-expanding stent proximate thedistal end, the inner member including a marker band disposed between adistalmost leading end of the self-expanding stent and a trailing end ofthe self-expanding stent, wherein the marker band indicates are-constrain limit of a partially-expanded, self-expanding stent; anouter member positioned about the inner member, the outer member beingslidable relative to the inner member in an axial direction; a holdingsleeve positioned within an interior of the stent so as to retain thepositioning of the stent; and a single inflatable device positionedabout the inner member, wherein the inflatable device is disposed solelybetween the holding sleeve and the distal end of the inner member;delivering the delivery system to a region of a vessel to be repaired;implanting the self-expanding stent into a wall of the vessel to berepaired; and inflating the inflatable device to assist expansion of theself-expanding stent.
 42. The method of claim 41, wherein delivering thedelivery system includes: positioning a medical guidewire; and guidingthe delivery system with the guidewire to the area of the vessel to berepaired.
 43. The method of claim 41, wherein inflating the inflatabledevice includes re-positioning the already-delivered delivery systemsuch that the inflatable device is properly aligned with theself-expanding stent.
 44. The method of claim 43, wherein re-positioningthe already-delivered delivery system includes slightly retracting thedelivery system from the point of the implantation of the stent.
 45. Themethod of claim 41, wherein inflating the device includes supplyingfluid to the inflatable device.
 46. The method of claim 45, whereinsupplying fluid includes supplying air.
 47. The method of claim 45,wherein supplying fluid includes supplying fluid by way of a lumenextending through the inner member.
 48. The method of claim 41, furthercomprising: deflating the inflatable device; and withdrawing thedelivery system from a patient's anatomy.
 49. The method of claim 41,further comprising: releasing a portion of the self-expanding stent to aposition corresponding with the marker band on the inner member; andre-constraining the self-expanding stent.